Water under pressure discharged from nozzles mounted on hand held guns is commonly used to clean surfaces as floors, walls and equipment and cut into concrete and soil. Guns having elongated tubes carrying water under pressure to nozzles which direct streams of water to selected locations are used to clean surfaces and objects. Examples of guns having nozzles for directing one or more streams of water under pressure to a selected location are shown by Andersen in U.S. Pat. No. 3,203,736, McDonald in U.S. Pat. No. 3,514,037 and Aarup in U.S. Pat. No. 3,536,151. These water cleaning systems use relatively low water pressure which does not erode the nozzle structure. Some of the nozzles are provided with transverse V-grooves to provide the nozzle with a broad or generally flat spray pattern. When these types of nozzles are used in ultra high water pressure systems, such as water pressure of 25,000 to 100,000 psi, the rapidly moving ultra high pressure water will erode the nozzle and substantially increase the orifice size. This makes the nozzle ineffective as an excessive amount of water flows through the orifice making it difficult for the pumping sysem to maintain the ultra high water pressure and substantially reducing the cutting and cleaning efficiency of the cleaning system.